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Click to go to Next Slide Most cells consume oxygen and produce carbon dioxide. The higher the rate of metabolism, the more oxygen used by the cells, and by the animal as a whole. One way to determine the basal metabolic rate (BMR), therefore, is to measure the amount of oxygen consumed by the animal. In general, larger animals consume more oxygen than smaller animals. Rubner's Surface Rule maintains that the metabolic rate is affected by the ratio of surface area to volume. According to this theory, cells in smaller animals maintain a higher metabolic rate to compensate for the greater amount of heat lost from their bodies. Click on the blackboard here to zoom in on a larger blackboard

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Click to go to Next Slide However, the same relationship between size and metabolic rate has been found in cold-blooded animals. These animals have body temperatures similar to the environment and do not compensate for heat loss. Clearly, other factors must be at work here. While you may predict that a larger animal will consume more oxygen than a smaller animal, the situation may be more complex if you compare the BMR (Basic Metabolic Rate) per gram of two animals. In this lab, the BMR’s of white rats of varying weights are determined by measuring their rates of oxygen consumption.

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Click to go to Next Slide This data is then used to calculate oxygen consumption per gram of body weight, and the results are graphed to allow comparison of oxygen/minute vs. oxygen/hour/gram. Using this information you should be able to draw conclusions about the effect of body mass on the metabolic rate. In this simulation the rate of oxygen consumption is measured from laboratory rats. You will determine the basal metabolic rate for each rat and calculate the rate of oxygen consumed by a gram of tissue. In this way the effect of body mass on oxygen consumption and on oxygen consumption per gram is determined.

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Click to go to Next Slide In the traditional wet lab a weighed rat is placed in a wire cage which is placed in a chamber containing soda lime. The chamber is sealed using a cork and soap bubbles are placed in the end of the calibrated tube. In this system the rat consumes oxygen and the soda lime absorbs exhaled carbon dioxide. Thus, as oxygen is used, the volume of air in the chamber decreases, and the bubbles move down the tube. The locations of the bubbles in the tube is measured every 15 minutes and the rate of oxygen consumption is calculated.

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:00 There are four rats in the rack. Select one of the rats by clicking on it. The rat will be weighed on the scale in grams. Record the weight of the rat in Data Table 1. You will be using all four of the rats in your experiment. If you have performed the experiment with all of the rats click here

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Mabel

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:00 There are four rats in the rack. Select one of the rats by clicking on it. The rat will be weighed on the scale in grams. Record the weight of the rat in Data Table 1 You have chosen Mabel g Click to go to Next Slide

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:00 After you have recorded the weight, and the name of the subject, click on Mabel to insert her into the wire cage inside the metabolic chamber g Click to go to Next Slide

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:00 Locate the beaker containing the bubble solution and pipette. Click on the blue pipette to inject the bubbles into the end of the tube leading from the respiratory chamber g Click to go to Next Slide

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:00 Measure the location of the extreme right side of the bubble in the tube. Record the value in Data Table 1 at TIME 0:00. (The value recorded should be 10) g Click to go to Next Slide

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Start Timer Start Timer :00 Click the Start Timer button for the timer to initiate the experiment. You will need to record where the edge of the bubble is at every 1 minute interval for 6 minutes. Record these values in Data Table 1 :301:001:302:002:303:003:304:004:305:005:306: g Click to go to Next Slide Stop the Timer and return to select a different Rat The Timer has started Wait for each 1 minute reading on the clock above to record your data

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Josie

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:00 There are four rats in the rack. Select one of the rats by clicking on it. The rat will be weighed on the scale in grams. Record the weight of the rat in Data Table 1 You have chosen Josie 12.0 g Click to go to Next Slide

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:00 After you have recorded the weight, and the name of the subject, click on Josie to insert her into the wire cage inside the metabolic chamber g Click to go to Next Slide

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:00 Locate the beaker containing the bubble solution and pipette. Click on the blue pipette to inject the bubbles into the end of the tube leading from the respiratory chamber g Click to go to Next Slide

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:00 Measure the location of the extreme right side of the bubble in the tube. Record the value in Data Table 1 at TIME 0:00. (The value recorded should be 10) 12.0 g Click to go to Next Slide

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Start Timer Start Timer :00 Click the Start Timer button for the timer to initiate the experiment. You will need to record where the edge of the bubble is at every 1 minute interval for 6 minutes. Record these values in Data Table 1 :301:001:302:002:303:003:304:004:305:005:306: g Click to go to Next Slide Stop the Timer and return to select a different Rat The Timer has started Wait for each 1 minute reading on the clock above to record your data

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Tex

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:00 There are four rats in the rack. Select one of the rats by clicking on it. The rat will be weighed on the scale in grams. Record the weight of the rat in Data Table 1 You have chosen Tex g Click to go to Next Slide

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:00 After you have recorded the weight, and the name of the subject, click on Tex to insert her into the wire cage inside the metabolic chamber g Click to go to Next Slide

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:00 Locate the beaker containing the bubble solution and pipette. Click on the blue pipette to inject the bubbles into the end of the tube leading from the respiratory chamber g Click to go to Next Slide

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:00 Measure the location of the extreme right side of the bubble in the tube. Record the value in Data Table 1 at TIME 0:00. (The value recorded should be 10) g Click to go to Next Slide

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Start Timer Start Timer :00 Click the Start Timer button for the timer to initiate the experiment. You will need to record where the edge of the bubble is at every 1 minute interval for 6 minutes. Record these values in Data Table 1 :301:001:302:002:303:003:304:004:305:005:306: g Click to go to Next Slide Stop the Timer and return to select a different Rat The Timer has started Wait for each 1 minute reading on the clock above to record your data

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Gertie

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:00 There are four rats in the rack. Select one of the rats by clicking on it. The rat will be weighed on the scale in grams. Record the weight of the rat in Data Table 1 You have chosen Gertie g Click to go to Next Slide

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:00 After you have recorded the weight, and the name of the subject, click on Gertie to insert her into the wire cage inside the metabolic chamber g Click to go to Next Slide

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:00 Locate the beaker containing the bubble solution and pipette. Click on the blue pipette to inject the bubbles into the end of the tube leading from the respiratory chamber g Click to go to Next Slide

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:00 Measure the location of the extreme right side of the bubble in the tube. Record the value in Data Table 1 at TIME 0:00. (The value recorded should be 10) g Click to go to Next Slide

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Start Timer Start Timer :00 Click the Start Timer button for the timer to initiate the experiment. You will need to record where the edge of the bubble is at every 1 minute interval for 6 minutes. Record these values in Data Table 1 :301:001:302:002:303:003:304:004:305:005:306:00 Click to go to Next Slide Stop the Timer and return to select a different Rat g The Timer has started Wait for each 1 minute reading on the clock above to record your data

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Questions

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:00 Construct Bar Graphs From the data you have collected and calculated, construct bar graphs which compare the weights of different sized rats and their oxygen consumption. Use Bar Graph 1 to compare Average Milliliters of Oxygen consumed per Minute vs the Weight of the individual animals. Use Bar Graph 2 to compare the Average Milliliters of Oxygen consumed per Hour per Gram vs the Weight of the individual animals. Formulas for manipulating the data are given in Table 2.Bar Graph 1 Bar Graph 2 Table 2 Click to go to Next Slide

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:00 Answer the Following Questions 1)Is there any relationship between the values for oxygen consumed / minute for each animal and the weight? 2) Is there any relationship between the values for oxygen consumed / hour / gram for each animal and the weight? 3) Why would a small rat have a different rate of oxygen consumption than a larger animal? Click to go to Next Slide Click Here to View a Printable Page of the Questions